Merlin will play Grandma Lois, the mother of Jessica Brody (Morena Baccarin). Boniadi, who is known for her recurring role on HIMYM as Barney's ex, Nora, will portray a young, but capable analyst named Fara.

Dana (Morgan Saylor) haters will be happy to hear that the eldest Brody child will be spending some time with a psychiatrist (Louie's Gary Wilmes). Dana will also befriend a new guy named Leo (The Last Keepers' Sam Underwood) who, natch, has a troubled past.

Prison Break alum Tracy Letts will be sworn in as Sen. Andrew Lockhart, the powerful and authoritative Committee Chairman. The Good Wife's Pedro Pascal will play Major Counsel David Portillo, a member of the Senate Select Committee on Intelligence. The President's National Security Advisor, Admiral Jim Pennington, will be portrayed by Lawrence Clayton (The Big C).

Season 3, premiering Sunday, Sept. 29 at 9/8c on Showtime, starts after the massive terror attack in the Season 2 finale that leveled the U.S. intelligence apparatus. An international manhunt for alleged terrorist Nicholas Brody (Damian Lewis) quickly kicks into high gear.